At the time of the invention, there were few technologies for the real-time monitoring of the injection of a stem cell transplant. Magnetic resonance imaging (MRI) allowed for the resolution of stem cells once they were inside the body. However, this method failed to provide any indication of the size or number of cells in the stem cell transplant. Moreover, this method required the stem cells to be labeled (i.e. loaded) with MRI contrast agents such as iron oxide. The use of these imaging agents however alter the biological activity of stem cells and compromise the ability of stem cells to impart a therapeutic effect in the body (see e.g. Cell Transplant. 2009 Dec. 18; and Neuroimage. 2010 Apr. 1;50(2):456-64).
What is needed in the art therefore was a method for the real-time monitoring of the administration of a stem cell transplant which monitors stem cells without the use of contrasting agents which can harm stem cell performance.